Imaging Research Laboratories, Robarts Research Institute, University of Western Ontario, London, Canada.
J Vasc Interv Radiol. 2010 Apr;21(4):562-70. doi: 10.1016/j.jvir.2010.01.016.
To develop and evaluate a technique for measuring the radial resistive force, chronic outward force, and dimensions of self-expanding stents.
A Mylar film was looped around the stent, threaded through two carbon fiber rods, and immersed in a 37 degrees C oil bath. A force gauge mounted on a micro-positioning stage was used to measure the applied forces. The apparatus containing the self-expanding nitinol stent (diameter, 40 mm; length, 80 mm) was placed inside a micro-computed tomographic (CT) scanner. At each stent deformation, the load was manually recorded from the force gauge and a micro-CT volume (isotropic voxel spacing, 0.15 mm) obtained. Stent diameter and length were measured from the images, and radial resistive force and chronic outward force were calculated for each deformation.
The stress-strain curves indicate that the stents exert much smaller maximum outward forces (1.2 N/cm) than the force that is required to compress them (3.6 N/cm). The forces were measured with a precision of +/-3.3% (standard deviation of five repeated measurements). The stent's diameter was measured with precision better than 0.3% and accuracy of +/-0.1 mm.
The authors have developed a radiographic technique that enables precise measurements of radial resistive force, chronic outward force, and the dimensions of self-expanding stents during deformation.
开发和评估一种测量自膨式支架径向阻力、慢性外向力和尺寸的技术。
将聚酯薄膜缠绕在支架上，穿过两根碳纤维棒，并浸入 37°C 的油浴中。一个安装在微定位台上的测力仪用于测量施加的力。将装有自膨式镍钛诺支架（直径 40mm，长 80mm）的装置放置在微计算机断层扫描（CT）扫描仪内。在每个支架变形时，从测力仪手动记录负载，并获得微 CT 体数据集（各向同性体素间距为 0.15mm）。从图像中测量支架直径和长度，并计算每个变形的径向阻力和慢性外向力。
应力-应变曲线表明，支架施加的最大外向力（1.2N/cm）远小于压缩它们所需的力（3.6N/cm）。力的测量精度为+/-3.3%（五次重复测量的标准差）。支架直径的测量精度优于 0.3%，准确度为+/-0.1mm。
作者开发了一种放射照相技术，能够在支架变形过程中精确测量径向阻力、慢性外向力和自膨式支架的尺寸。
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